1. Field of the Invention
The present invention relates to a relay communication system that enables client terminals connected to local area networks (LANs) to communicate with one another beyond a wide area network (WAN).
2. Description of the Related Art
By using a virtual private network (VPN), a client terminal can communicate with another client terminal remotely located beyond a WAN. However, it is difficult for the VPN to construct a network having expandability and flexibility.
A relay communication system disclosed in Japanese Patent Laid-Open Publication No. 2008-129991 can construct a network which appears as if remote LANs were directly connected to one another in a similar way to the VPN. This relay communication system is superior in terms of expandability and flexibility to the general VPN in that it is possible to dynamically change a group relationship among the LANs, and so on.
In the relay communication system disclosed in Japanese Patent Laid-Open Publication No. 2008-129991, the respective relay servers share identification information of the client terminals connected to the respective LANs, thus enabling communication among the client terminals. Specifically, association information between identification information of the relay servers and identification information of the client terminals is shared by the entire network, thus making it possible for the relay servers to relay communication packets among the client terminals.